1. Field of the Invention
The present invention relates to agricultural field and soil enclosure means for seasonal hot bed and greenhouse and more specifically, to the agricultural science and technology for creating optimal spectrum and sunlight illumination atmosphere for green plants under a seasonal thin-film covered hotbed condition.
2. Description of the Related Art
Since the foundation work of research by Russian natural scientist K. A. Timiriazev in 1896-1919, it has been for sure that sunlight is absorbed into the leaves of green plants by a green pigment, which absorbs red and blue light, but reflects green light, causing the leaves to appear green. This light energy is then converted into a chemical energy in the form of starch or sugar: 6CO2+6H2O→C6H12O6+6O2.
This equation translates as six molecules of water (6H2O) plus six molecules of carbon dioxide (6CO2) produce one molecule of sugar (C6H12O6) plus six molecules of oxygen (O2).
Since the creation of phosphor light source in 1930˜1950, all greenhouses and hotbed provide red and blue radiation light sources. Under the illumination of radiation light sources, the amount of vegetables and fruits obtained from the enclosed soil equipment is greatly increased. Solar radiation goes through a polyethylene thin film and the pigment of the polyethylene thin film is modified to, for example, light blue or rose. In the years of 1980˜1990, light conversion agricultural films were appeared. The radiation of these light conversion agricultural films include 5˜6% red light. This red light reacts with 6% original solar ultraviolet radiation. These agricultural films were patented in many countries around the world, such as Russian Patent 2160289 (inventor Soschin. N et. al.), Russian Patent 2064482 (inventor Soschin. N et. al.), U.S. Pat. No. 6,153,665 (inventor Goldburt et. al.), Euro Patent 999/35595 (inventor Bolschukxin W. et. al.), and Mexico Patent MX 01004165A (inventor E. T. Boldburt et. al.). The invention adopts the aforesaid patents as reference objects. In the aforesaid patents, a first generation light conversion agricultural plastic film utilizes Y2O2S:Eu based narrowband red phosphor, which has best conversion efficiency as known. The half-wave width of the spectrum band is smaller than 5 nm, assuring enhancement of red quantum concentration on the surface of green plants. Under the effect of light conversion agricultural plastic films, the production of vegetables and fruits in hotbed is increased by 20˜75%, and the nutrition composition of vegetables and fruits is substantially improved, for example, vitamin and minor element content of vegetables and fruits is increased.
Although the first generation light conversion agricultural plastic films have been intensively used for agricultural purposes, they still have drawbacks. At first, light conversion involves red spectrum region only, giving no effect on the second shortwave of blue spectrum. Under this condition, photosynthesis is periodically destroyed. Further, reduction of transmissive light in blue and green spectrum regions of the light conversion agricultural plastic films results in extended growth period of greenhouse crop. The creation of a thin film having blue-red re-radiation characteristic eliminates a part of the aforesaid drawbacks. US2000/24343 (inventor Soschin. N. et. al.) discloses a similar design. The invention utilizes this invention as a prototype. The blue and red phosphors filled in this agricultural plastic film create supplementary light for plants. Using blue and red conversion radiator means in a film layer is a continuation and development of this concept, and has become a patent of France researchers (see WO 00/24243, inventor Blanc. W. et. al.). They created a single-component dual-band phosphor based on Ba3MgSi2O8:Eu+2Mn+2. With respect to the fabrication of agricultural plastic films, the concept of the aforesaid patent assures its advantages. However, in the literature, we did not find any strick proof of the applicability of this agricultural plastic film. The application of this dual-band phosphor may be constrained to its defect because photosynthesis requires all the three spectrum regions: blue, green and red at different radiation amounts.
Actually, according to data from modern researchers, spectrum illumination has the following physiological meanings: 1.280˜320 nm UVB light will damage plants; 2. Radiation of UVB and near UVB light at a small amount has a great concern with growth regulation of plants; 3. Purple and blue light are requisite for photosynthesis and regulation of upper green leaves (plant root system); 4. Green and yellow radiation provides a long-lasting effect, and is partially absorbed by lush green leaves and dense tender branches of plants; 5. Orange and red radiation is necessary for photosynthesis; 6. 700˜750 nm dark red radiation is the message communication path for green plants; and 8. 1200˜1600 nm infrared radiation heats and dissolves plant nutrients. From this short catalog, we obtain the conclusion that full-spectrum illumination in radiation is necessary.